[This is the English version of the AKARI (ASTRO-F) Newsletter #21 dated
26th February, 2008.]
############### ASTRO-F Newsletter Vol 21 February 2008 ###############
This newsletter E-mail will be circulated occasionally to report the
up-to-date status of the AKARI (ASTRO-F) project. It is sent to the
iris_observer mailing list, which includes anyone interested in the
AKARI project.
####################### Happy Birthday, AKARI! #########################
AKARI (ASTRO-F) launched on February 21st (UT), 2006, recently celebrated
its two year birthday. AKARI has successfully carried out its mission
until the boil off of the liquid Helium in August last year, and now is
preparing for Phase 3 observations with the remaining IRC/NIR channel
and mechanical coolers. The AKARI team will continue to endeavour to
produce as many valuable scientific results as possible during this final
phase of the mission.
In this newsletter we will report on the recent activities for Phase 3.
####################### Orbit control manoeuvre ########################
An additional orbit control manoeuvre was performed last December.
AKARI orbits around the Earth along the twilight zone on a path known as
a `Sun-Synchronous polar orbit'. In order to maintain this orbit the
relation between the altitude, and the angle between the orbital plane
and the polar axis of the Earth must be preserved. However, during the
mission, evaporating gas from the liquid Helium blew out from the
spacecraft causing an acceleration such that the altitude of the orbit
gradually increased during the mission. This effect caused a deviation
of AKARI's orbit from the ideal one. If this situation was allowed to
continue, there would be problems with both the power supply as well as
stray light from the Earth that would disturb future observations. We
therefore decided to perform the orbit change manoeuvre and return the
spacecraft back to a Sun-synchronous orbit.
The operation was carried out on December 4th and 7th. It was the first
manoeuvre since the very beginning of the mission and careful
preparations and rehearsals were made from late November. The operation
plan was further complicated, by the constraint of having to avoid any
light from the Sun or the Earth leaking inadvertently into the telescope.
During the actual operation we also encountered several nerve racking
problems, however, thanks to immediate action by the control experts,
every obstacle was overcome, and we succeeded in sending AKARI on the
way back to the ideal orbit gradually over a few years. We extend our
thanks to the team members and supporting groups.
##################### Tuning the IRC/NIR detector ######################
The temperature attainable, solely by the mechanical coolers is
significantly higher (about 40 K) than that achieved using liquid Helium.
The IRC team have been endeavouring to tune the instrument to an optimal
condition under these circumstances. Since it is our first experience to
drive the detectors under such conditions the operation must be carefully
executed. This tuning is expected to be concluded by the end of February,
after which calibration observations will commence.
##################### Phase 3 observation planning #####################
AKARI Phase 3 observations will consist of Mission programmes (MP) and
Open Time programmes (OT). MP proposals have already been submitted from
the science working groups and are now under screening by the Scientific
Advisory Committee (SAC). We expect that the MP programmes will be fixed
by middle of March and we will then proceed with the call for Open Time
observations. Please stay tuned!
############################ Mission review ############################
As part of the process of stepping towards Phase 3 of the mission, the
AKARI project is examined in its results obtained so far and scope to
continue the mission. The project summary document was submitted to the
reviewing committee at the end of January. The committee's report will
be available in mid March.
####################### What's next for AKARI ##########################
* Preparation towards Phase 3 of the mission continues.
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#### AKARI Newsletter Vol.21 (February 2008)
#### This issue is brought to you by Issei Yamamura
#### English translation by Chris Pearson
####
#### AKARI Web: http://www.ir.isas.jaxa.jp/AKARI/
#### AKARI Helpdesk at ISAS: iris_help @ ir.isas.jaxa.jp
####
#### The AKARI Newsletter is open for any researchers who are interested
#### in observations with AKARI. Subscription/unsubscription of this
#### Newsletter, and any matters or general opinions related to AKARI,
#### are also sent to the Helpdesk.
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